Heat transfer device



July 16, 1935. w. Y. LEWIS HEAT TRANSFER DEVICE Filed July '7, 1952 4Sheets-Sheet 1 pwwmz %w w July 16, 1935. w. Y. LEWIS HEAT TRANSFERDEVICE Filed July '7, 1932 4 Sheets-Sheet 2 July 16, 1935. ,w w s2,008,076

HEAT TRANSFER DEVICE y 1935- W. Y. LEWIS HEAT TRANSFER DEVICE Filed July7, 1952 4 Sheets-Sheet 4 Fig.9.

0 .i O p 0 A O a R o n m J C K on u o co "a oo olo no n an- 00 0 0000000 000. I one 0006 I coo 0000 0 0 a o x 0 a w. 0 6 IR 0 n C r PatentedJuly 16, 1935 t a UNITED STATES PATENT OFFICE Application July 7, 1932,Serial No. 621,250

' In Great Britain July 20, 1931 5 Claims. (01. 125F282) The inventionrelates to heat-transfer devices shown therein consists of two parallellegs a. I). particularly suitable for water-tube boilers. i er nn ct y an to form a U- b A main object of the present invention is to the openends of which are secured by any suitprovide practicable forms ofwater-tube boiler, able means to a wall, d, of a suitable receptaclesuitable in particular for modern high pressures, or container, a d aner tu 6, a a g d withand of reduced weight and cost of manufacture inpn0f the y this inner e bein comparison with the present boilers they areme pen tb th nd and p in l n e intended to replace, length of its U-leg,a, to the beginning of the With such a main object, thepresent-invenbend or thereabouts, the upper end being secured tionconsists in the improved forms of U-Fieldto .a s cw f, or h rwise ermnated or tube water-tube boiler and in certain novel forms d i ySuitable an er. 7 of U-Field-tube, unit applicable in such boilersIIISOme Cases, an inner tube m y be Provided as hereinafter describedand defined in the claims neach leg of the U. appendant hereto, v Theinner 'tube, 6, maybe centralized in its In order to make clear thenature and. operal by Suitable d v ces uch as the fins h. tion of thepresent invention, I propose first to According o a fi d form ofU-Fie1dtube describe by way of example certain forms of unit Figures 2,3 nd 4) the u er tube com- U-Field-tube unit suitable for the purposesof the prises the Straight legs, d b, united by the present inventionand subsequently to describe bend, and an inner tube, 61, inserted i ech practicable forms of high-pressure U-Field-tube h ds of these innertubes being in S water-tube boilers, cases flexible as indicated inFigure 2 and over- Referring with this object to the accompanyppi Over at preferab y D S ing drawings, which are of a diagrammatic na centrallytt bOttOm 0f the T0v p ture;- vide for the overlap, which mayextend evenFigure 1 shows a sectional elevation of a form right round the bend, e eds of the inner 25 of U-Field-tube unit according to the present tu arein some cases Offset s shown n invention with an inner tube-in one leg;ure 3, Wh if desired y y in addition be Figure 2 shows a sectionalelevation of anv ail-Shape in Cross-Section as S own in other form ofU-Field-tube unit having a fiexi- F gure 4, the jux p flats of the b bleinner tube inserted in'each leg, the inner secured by v Other u tablemea s, 30

tubes overlapping withinthe bend, such as a binder.

Figure 3being acorresponding plan, and According to another form ofU-Field-tube Figure 4 a cross-section on theline 44 of Figunit ure thetwo le s, b, are conure 2; nected at their'upper ends in the commonjunc- Figure 5 shows a sectional elevation of a modi- D on-p g,eXpaneien i e Wa l Of a 35 fied form in which the two legs of the U aresuitablecontainer, the inner tube, e being forked united at their upperends, f as shown and the two branches, 6*, 6 passing Figure 6 being asimilar view of yet another down the respectivelegs of the U.. In thiscase, form in which a plurality of Us are connected the innertubes', 6,0 are conveniently positioned at corresponding ends in common jun ti'eccentrically in their outer tubes and held in 40 i place by theinteraction of the inner and outer Figure 7 shows a sectional elevationof an equivforks-t l i alent' form of U-Field-tube unit in which the Wnth tw l s, a, f the U a a ra d bend of the u is replaced by a junctionbox; o e together as n Figure he turn of the u Figure 8 shows an endelevation taken on the may take the form f a p d b d, Well 45 line 8-8of Figure9 of a modified Yarrow-ty known as applied to superheaterelements, or water-tube boiler embodying U-Field-tube'units, s shown inFigure h w r s of the s Figure 9 being a corresponding side view; and yb nn c e y a j -p 9 si i ar Figure 10 shows a sketch of a modificationof to that connecting the upper ends, but modified the Johnson type ofwater-tube boiler including by the; provision of a screwed cap, 9removable U-Field'et'ube units in its structure. for cleaning orinspection purposes.

Where desirable the same reference symbols Or again, two Us with legs a12 and a b are used in the different figuresto denote corarranged, e.g., one within the other, as shown in responding parts. t Figure 6, oralternatively side by side, are con- 'Referring to Figure 1, the-U-Field-tube unit nected at their corresponding upper ends in the 55common junction-pieces, g 9 the inner tubes e 6 being forked as inFigure 5 to form branches, e e

The structural details of a U-Field-tube unit in accordance with thepresent invention may be modified as required to meet the conditions ofits particular application.

Thus, the inner tube, instead of being rigid may be flexible or partlyrigid and partly flexible, or it may be constructed in a single lengthor of a series of detachable lengths, particularly with a view toobtaining ready access to the mouth of the outer tube for theapplication and operation of suitable expanding tools. I 7

Further, in certain applications of the invention, as exemplified below,oneior more legs of the device, instead of being straight, may be curvedso as to provide, e. g., a Water-tube wall of any desired contour; inother cases, U-lgs arranged at any desired angle may be substituted forthe parallel legs described.

When the inner tube is rigid, it may be inserted into the outer tube,and bent simultaneously therewith to form a complete unit ready. forassembly. 7 I r In some cases, the interconnection between the legs of aU,-may take the form of a junction box, 0?, (see Figure '7) serving asthe equivalent of the U bend.

, If desired, in some applicaticns, suitable draining arrangements maybe provided at the point or region of interconnection of the legs or ashort length of tube proj-ectingfrom the bend of the U may be providedas a mud-box or sump, its end being closed solid or by aremovable cap orplug; if the end is closed, it may be sawn oil? for inspection purposes,cleaning or the like and re-closed, e. g., by welding. Y

The inner tubes may be positioned in any suitable manner as, e; g., bysuitable distance pieces within the outer tubes, from which they projectsomewhat, or their projecting ends may be secured to one or more platesforming a partition or diaphragm of a receptacle or container as abovementioned. v

Turning now. to the specific application of a U-Field tube unit inaccordance'with the invention, for example, to one form of thewell-known high-pressure Yarrow water-tube boiler (see Figtires 8 and 9)a steam-and-water drum, 7c, is provided and depending at a considerableangle to the horizontal therefrom on each side of the furnace, one ormore banks, C, C, of closely-spaced U -Field-tube units of a lengthconsiderably great.- er than the diameter of the steam-and-water drum;the planes of the Us in the example shown are parallel to the axis ofthe drum, the open ends of the legs being expanded into localized groupsof holes corresponding to the banks and. drilled in the drum walls orotherwise secured thereto, while the bends, 0', rest in more or lessupright plates, 121., provided with slots, 11.

Within one or'bothlegs of each U, an inner tube is positioned, the lowerend of which is open while the upper end is connected to a partition, 0,within the drum, is.

In a modified form, instead of a single upper drum, two or moreinterconnected upper drums may in some cases be used.

The planes of the Us instead of being parallel to the axis; may in othercases be at right angles to the axis of the drum or drums, k, or anyother angle desired. j

When the planes of the Us are, for example, at right angles to the axisof the drum or drums,

the hydraulic mean depth of thewater flow may be varied by adjusting thediameter of the inner tubes in the two legs without altering thediameter' of the outer legs. Thus, for example, the U-leg adjacent tothefurnace where the rate of steam generation is high, may have an innertube of small diameter or even be without an inner tube, while the legof the U remote from the furnace may be fitted with an inner tube oflarge diameter.

The transverse end wall or walls of the combustion chamber may also becomposed of U- Field-tube units in one or more rows.

Thus, according to one plan, the Us' depend from the steam-and-waterdrum in groups, the legs of any one group, for example, being paralleland the groups themselves arranged fanwise to cover the relevant area.

Or as shown in Figures 8 and 9, the U-legs, 1, preferably arranged withtheir plane at rightangles to the axis of the drurn totform the endwalls, maybe extended as'at s to form the floor of the combustionchamber. a r

Or again, as shown in the same figures, one leg, t of'a U -Field-tubeunit may form part of one end wall and be extended under'the combustionchamber to form a fiooras at u and pass on to the other leg, t formingpart of the other end wall. I To minimize the length of suchend-wall andfloor tubes exposed to maximum furnace heat, the floor tubes may, ifdesired, be extensions of tubes forming the 'sidebanks. I V

In particular, tubes of the row or rows most remote from the furnace areof low value as regards evaporation and are therefore Well adapted tosustain an increased steam production if extended to form the floor ofthe furnace chamber. Referring to Figure 10, a modified form of Johnsonboiler having an upper and a lower drum connected by outwardly-curvedsteamgenerating. tubes is shown, according to which the lower drum isomitted and the steam-gencrating tubes replaced by U-Field-tube' units,

Figures 8 and 9, but with their legs, 11; outwardly curved and theirbends, w, disposed as desired, while according to another arrangement,U-Fieldtube units, '23, preferably thosemost exposed-to the maximumheat, pass completely round the combustion chamber in a transverseplaneso as to form part of both side walls and the floor.

Both arrangements, if desired, may be used in the same boiler. I i

End walls also composed of U -Field-tube units may be used inconjunction with'any such modified boiler..- I I I a Instead oi boilersof more or less symmetrical design, as above described, according to amodified form, the steam-and-water drum is arranged at one side, withthe bank of Us extending laterally to form the crown of the combus;

The present invention is also applicable to' other types of water-tubeboiler embodying in their structure a steam-and water drum 'and at leastone header or at least one header and one other drum connected to thesteam-and-water drum.

In some forms of water-tube boiler, according to the present invention,the legs of a U may be secured to difierent receptacles or containers.

As compared, for example, with Yarrow or other boilers having two ormore drums connected by-water-tubes as heretofore constructed, it willbe seen that with the U-Field-tube Yarrow-type boiler described indetail above, only one drum is required, and in the case of modernhigh-pressure boilers, the elimination of one or more large drums underthe full pressure of the boiler and forged, it may be, out of solidmetal by expensive processes, leads to a material reduction in theweight and cost of manufacture including the work involved in drillingand so forth, and also to a material reduction in the number oftube-anddrum joints.

Similar advantages arise in the case of boilers having bottom headers.

The elimination of such drums (or headers) by the use of U-Field-tubeunits is rendered f asible and practical by the common practice at thepresent day of feeding water-tube boilers with practically pure feedwater so that the necessity for mud-collecting space in the lower drumsor headers with their blow-down and drain connections is virtuallyeliminated.

Other important advantages of the invention as applied to the Yarrowtype of boiler, for example, are that the replacement of a lower drum byan upright support plate carrying the ends of the U-Field-tube units, asin Figures 8 and 9, ensures greater heating surface in the same or ineven less space and also a gradual reduction in the area of the gaspassage through the nest of tubes, a feature that is very desirable inorder to maintain a good velocity of the progressively cooled gas overthe heating surface.

Further, the Us are free to expand and contract and the application ofsoot-blowing apparatus for action along the length of the tubes isfacilitated by the absence of bottom drums.

In addition, as compared with high-pressure water-tube boilers of thedrum or drum-andheader types in use at the present time, the presentinvention has the advantage that Us, particularly with overlapping innertubes as shown, for

example, in Figures 2, 3 and 4, assist an even and uninterrupted flowinone and that the correct direction. Furthermore, when more than oneinner tube is provided in a unit, if the rate of steam generation isgreater in one leg than in another, more than one source of feed-Watersupply is provided or is available, or even if one such inner tubeshould be more or less choked, circulation can continue by way ofanother inner tube or tubes.

It will be understood that while specific forms of the invention havebeen described in order to make clear its general nature, the scope ofthe invention as set forth in the claims appendant hereto is notrestricted to such specific forms, and in particular, any other suitableform of U-Fieldtube unit may be used.

Having now described my invention, what I claim as new and desire tosecure by Letters Patentiszl. Heat-transfer apparatus comprising a U-Field-tube unit having an inner tube in each leg, the two inner tubesoverlapping and the overlapping parts being flattened in cross-section.

2. Heat-transfer apparatus comprising a U- Field-tube unit having aninner tube in each leg,

the two inner tubes overlapping and the overlapping parts beingflattened in cross-section and secured together.

3. Heat-transfer apparatus comprising a combustion chamber and at leastone container and U-Field-tube units each comprising outer and innertubes, operatively associated therewith and individually encircling saidcombustion chamber.

4. Heat-transfer apparatus comprising a combustion chamber, a horizontalcontainer of elongated form and U-Field-tube units each comprising outerand inner tubes, operatively associated with said container and formingwalls of said combustion chamber, the planes of certain of the Us ofsaid units lying parallel to the length of said container.

5. Heat-transfer apparatus comp-rising a U- Field-tube unit having aplurality of Us, a common junction-piece connecting the upper ends ofcorresponding legs of different Us and at least one forked inner tubepositioned with the branches of the fork in a plurality of the U-tubelegs which are so connected.

WILLIAM YORATI-I LEWIS.

